California's Title 24 Building Energy Efficiency Standards require "cool roof" products on most residential re-roofing projects. A cool roof reflects more of the sun's energy (higher Solar Reflectance, or SR) and emits absorbed heat more efficiently (higher Thermal Emittance, or TE) — resulting in a lower roof surface temperature.
Why cool roofs matter in California:
- A standard dark asphalt shingle can reach 150–180°F in the California sun. A Title 24-compliant cool roof may stay 50–80°F cooler.
- Cooler roof = lower attic temperature = less heat transferred into living space = lower AC energy use
- The energy savings from a cool roof can be 15–25% of cooling costs in hot CA climate zones
- In Central Valley cities like Fresno and Bakersfield, where AC runs 5+ months annually, cool roof savings are particularly meaningful
Title 24 cool roof requirements:
- Low-slope roofs (2:12 pitch or less): minimum Solar Reflectance of 0.63 and Thermal Emittance of 0.75 required statewide
- Steep-slope roofs (above 2:12): requirements vary by climate zone. Most of CA requires minimum SR of 0.20 or use of ENERGY STAR-rated cool roof products
- Products must be listed on the CRRC (Cool Roof Rating Council) Rated Products Directory
- Your licensed C-39 contractor is responsible for specifying compliant products and documenting compliance on the permit application
Cool roofs and solar panels work synergistically — a cooler roof surface means cooler solar panels, and solar panels operate more efficiently at lower temperatures. A combined cool roof + solar installation is a genuinely excellent energy upgrade for California homes.